In recent years, videoconferencing over the Internet and/or wireless networks has gained increased popularity. In conventional videoconferencing systems, multipoint control units (MCUs) have been employed in conjunction with the Internet and/or wireless networks to enable collaboration among groups of participant devices in videoconferences by performing various functions such as mixing, synchronizing, and/or transcoding video and/or audio bitstreams generated by the respective participant devices.
However, maintaining acceptable levels of video quality for such participant devices engaged in videoconferencing over the Internet and/or wireless networks can be problematic because the participant devices can often have different bandwidth, resolution, and/or other device requirements. To obtain acceptable levels of video quality for such participant devices, particularly those that operate at different bandwidths, MCUs employed in videoconferencing may find it necessary to encode video and/or audio bitstreams generated by one or more of the respective participant devices multiple times, thereby increasing the processing requirements of the video conferencing system.
Some conventional videoconferencing systems have employed scalable video coding (SVC) techniques (i.e., the Annex G extension of the H.264/MPEG-4 Advanced Video Coding (AVC) video compression standard) to effectively share an encoder in an MCU among multiple participant devices, allowing the shared encoder to generate video bitstreams that cover multiple bit rates, or a range of bit rates. However, such SVC techniques can be complicated and costly to implement, and, for at least these reasons, have not been widely deployed to date in videoconferencing systems.